The present invention relates to a tubing connector and more particularly to a releasable connector suitable for constructing enclosures for machinery.
Various machinery requires both a safety enclosure to prevent injury during operation, and periodic maintenance. While it is known to construct such enclosures, there has been a conflict between building a strong structure and building a structure that allowed easy disassembly for maintenance.
U.S. Pat. No. 3,008,741 issued Nov. 14, 1961 for “Structural Apparatus,” describes a corner fitting suitable for assembling a cabinet. The corner piece includes at least two arms which are insertable into the ends of square tubing. The arm defines a longitudinal diagonal slice separating the end of each arm into a first triangular portion and a second triangular portion. A diagonal screw in the first triangular portion is accessed through a hole in the corresponding tubing. The end of the screw abuts the second triangular portion and tightening the screw spreads the triangular portions apart, thereby creating a friction fit between the arm and the tubing. Although the apparatus of the '741 patent appears to provide a strong and easily assembleable and disassembleable tubing connector, repeated assembly and disassembly causes the screw to become loose, and eventually wears out the fitting.
U.S. Pat. No. 3,545,625 issued Dec. 8, 1970 for “Modular Construction Frame,” describes a corner fitting similar to the fitting of the '741 patent, the difference being that the fitting of the '625 patent includes slices forming an inverted “T” (contrasted to the diagonal slice of the '714 patent), and the screw includes a tip intercepting the “T”, and forcing the slices to separate. Repeated assembly and disassembly of the '625 fitting also causes wear of the fitting.
Other fittings have used plastic mating surfaces, but have not provided the combination of strength and repeated assembly and disassembly desired. The plastic mating surfaces make disassembly and re-use very difficult or impossible because of the binding the plastic fitting and the interior of the tubing.